Projection type video display

ABSTRACT

An ion wind generator ( 20 ) is arranged on one side of a light source ( 1 ). The ion wind generator ( 20 ) produces an air current by negatively ionizing air by corona discharges at a needle electrode ( 21 ), or negative side, and drawing the negatively-ionized air at a cylindrical electrode ( 22 ), or positive side. The air current blows toward the light source ( 1 ) and removes heat generated by the light source ( 1 ). An ultraviolet ray from the light source ( 1 ) is introduced to a vent of the ion wind generator ( 20 ) by a first dichroic mirror ( 4 ) and a ultraviolet ray reflection mirror ( 17 ). Though air exhausted from the vent includes ozone (o 3 ) produced by corona discharges, the ozone is decomposed by the ultraviolet ray.

TECHNICAL FIELD

The present invention relates to a projection type video display such asa liquid crystal projector, and the like.

BACKGROUND ART

A projection type video display is so configured that light emitted froma light source is modulated by a light valve such as a liquid crystalpanel to be projected, so that it must comprise a high-luminance lightsource. Consequently, measures to prevent heat generated from thehigh-luminance light source itself and heat generated when light isabsorbed in a light polarizing plate in the liquid crystal panel orvarious types of optical components are required. Conventionally, aprojection type video display has a structure in which air is sucked andexhausted and heat is released from the device by rotating a fan with amotor (see JP-A-2001-222065)

In a suction and exhaust mechanism using motor driving, however, noisesare produced due to suction and exhaust sound by rotating sound of amotor and hissing sound of a fan. As a result, there is a disadvantagethat the noise produced by the suction and exhaust sound is offensive tothe ear when a projector is used.

DISCLOSURE OF INVENTION

In view of the foregoing circumstances, it is an object of the presentinvention to provide a projection type video display capable of reducingnoises of air suction and exhaust up to almost soundless state.

In order to solve the above-mentioned problem, a projection type videodisplay according to the present invention modulates a light emittedfrom a light source with a light valve to project the modulated lightand is characterized in that there is provided a wind blower whichgenerates an air current by ionizing air and molecules in the air usingan electrode on one side and drawing ions generated by the ionization byan electrode on the other side, and in that an ultraviolet ray emittedfrom the light source is spectrally separated to apply to a windgenerated by the wind blower. Also, the projection type video displaywhich modulates a light emitted from a light source with a light valveto project the modulated light is characterized in that there isprovided a wind blower which generates an air current by ionizing air bycorona discharges using an electrode on one side and drawing the ionizedair by an electrode on the other side.

In the above-mentioned configuration, the wind blower generates an aircurrent by electrically moving the ionized air and the like. As aresult, unlike a wind blower that generates a wind by rotating a fan,the wind blower produces no rotation noise and reduces noises of airsuction and exhaust up to almost soundless state.

Ozone can be decomposed by the ultraviolet ray emitted from the lightsource, even if ozone is generated by discharges. Furthermore, theconfiguration allows an ultraviolet ray which is unnecessary indisplaying a video to be effectively utilized.

It is possible to adopt a configuration that plural electrodes on oneside are arranged in parallel or approximately in parallel and pluralelectrodes on the other side corresponding to the electrodes on one sideare arranged in parallel or approximately in parallel. Such aconfiguration enables the wind power generated by the wind blower to bemore high-powered. Alternatively, plural electrodes may be arranged asan electrode on one side and a mesh electrode may be arranged as anelectrode on the other side. In such a configuration, it is easy torealize the reduced cost and the light weight.

An electrode on one side may comprise a metal plate having pluralpointed portions on an edge. An assembling process is easier in such aconfiguration, compared with a configuration in which plural needleelectrodes are arranged. Also in such a configuration that an electrodeon one side comprises a metal plate having plural pointed portions, amesh electrode may be arranged as an electrode on the other side.Furthermore, as an electrode on one side, plural metal plates havingplural pointed portions may be arranged with keeping certain intervalseach other. The electrode on one side having plural pointed portions maybe made by etching metal plate. By adopting etching process, the pointedportions can be formed in an adequate shape.

Also, a projection type video display that modulates light emitted froma light source with a light valve to project the modulated lightaccording to the present invention is characterized in that there isprovided a wind blower which generates an air current by ionizing airand molecules in the air using an electrode on one side, or upstreamside of air current, and drawing ions generated by the ionization by anelectrode on the other side, or downstream side of air current and aplurality of said electrodes on one side are arranged and as anelectrode on the other side, a mesh electrode is arranged so as to crossthe direction of air current.

A projection type video display that modulates light emitted from alight source with a light valve to project the modulated light accordingto the present invention is characterized in that there is provided awind blower which generates an air current by ionizing air and moleculesin the air using an electrode on one side, or upstream side of aircurrent, and drawing ions generated by the ionization by an electrode onthe other side, or downstream side of air current and, said electrode onone side comprises a metal plate having plural pointed portions on anedge.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a projection type video display according toan embodiment of the present invention.

FIG. 2 is an explanatory view showing a configuration of an ion windgenerator.

FIG. 3 is an explanatory view showing another configuration of an ionwind generator and its layout.

FIG. 4 is a perspective view showing a different configuration of an ionwind generator and its layout.

FIG. 5 is a perspective view showing another different configuration ofan ion wind generator.

FIG. 6 is a perspective view showing another different configuration ofan ion wind generator its layout.

FIG. 7 is a perspective view showing another different configuration(structure of electrodes) of an ion wind generator.

BEST MODE FOR CARRYING OUT THE INVENTION

A projection type video display of the present invention is nowdescribed referring from FIG. 1 to FIG. 7.

FIG. 1 is a diagram showing an optical system of a three-panel colorliquid crystal projector. A light emitter 2 in a light source 1 iscomposed of an ultra-high pressure mercury lamp, a metal halide lamp, axenon lamp, and the like, and light irradiated therefrom is emittedafter being changed into parallel light, for example, by a parabolareflector 3.

A first dichroic mirror 4 is arranged at an oblique angle of 45 degreesto the direction of light emission of the light source 1, so thatultraviolet ray is reflected in a crosswise direction and components ofwavelength other than ultraviolet ray are transmitted.

A second dichroic mirror 5 transmits light in a red wavelength band,while reflecting light in a cyan (green+blue) wavelength band. The lightin the red wavelength band which has passed through the second dichroicmirror 5 is reflected from a mirror 6 so that its optical path ischanged. The red light which has been reflected from the mirror 6 isoptically modulated by passing through a transmission type liquidcrystal light valve for red light 31 through a condenser lens 7. On theother hand, the light in the cyan wavelength band which has beenreflected from the second dichroic mirror 5 is introduced into a thirddichroic mirror 8.

The third dichroic mirror 8 transmits light in a blue wavelength band,while reflecting light in a green wavelength band. The light in thegreen wavelength band which has been reflected from the third dichroicmirror 8 is introduced into a transmission type liquid crystal lightvalve for green light 32 through a condenser lens 9, and is opticallymodulated by passing through the liquid crystal light valve 32. Thelight in the blue wavelength band which has passed through the thirddichroic mirror 8 is introduced into a transmission type liquid crystallight valve for blue light 33 through mirrors 11 and 13, relay lenses 10and 12, and a condenser lens 14, then the light is optically modulatedby passing through the liquid crystal light valve 33.

Each of the liquid crystal light valves 31, 32, and 33 comprises anincidence-side polarizing plate, a panel constructed by sealing a liquidcrystal between a pair of glass boards (where a pixel electrode and analignment film are formed), and an emission-side polarizing plate.Modulated lights (video lights in respective colors) which have beenrespectively modulated by passing through the liquid crystal lightvalves 31, 32, 33 are mixed by a dichroic prism 15, to be a color videolight. The color video light is enlarged and projected by a projectionlens 16 and is displayed on a screen (not shown).

An ion wind generator 20 is provided at the side of the light source 1.As shown in FIG. 2, the ion wind generator 20 ionizes air by coronadischarges using a negative-side needle electrode 21 and draws theionized air by a positive-side cylindrical electrode 22 to produce anair current. A high-voltage generating circuit 23 receives voltagesupply from a power supply 24 to generate a high voltage ranging from afew kilovolts to ten and several kilovolts and applies the high voltageto the electrodes 21 and 22.

As shown in FIG. 1, since an air supply port of the ion wind generator20 faces the light source 1, the light source 1 is exposed to agenerated air current by the ion wind generator. As a result, the aircurrent removes heat from the light source 1. An ultraviolet rayconverging lens 18 and an ultraviolet ray reflection mirror 17 areprovided in a position where the ultraviolet ray reflected from thefirst dichroic mirror 4 strikes. The ultraviolet ray generated in thelight source 1 is converged to be introduced to the vicinity of the airsupply port of the ion wind generator 20 by the ultraviolet rayconverging lens 18 and the ultraviolet ray reflection mirror 17.Although the air supplied from the air supply port of the ion windgenerator 20 includes ozone (o₃) produced by corona discharges, theozone is to be decomposed by the ultraviolet ray generated in the lightsource 1. An ultraviolet ray is unnecessary light in video projection.Rather, it is desirable that an ultraviolet ray is eliminated inilluminating light. In the present embodiment, an ultraviolet ray is notonly eliminated but is effectively utilized to decompose ozone includedin air supplied from the ion wind generator. In the above-mentionedconfiguration, the air supply port of the ion wind generator 20 isarranged to face the light source 1 to blow cooling air to the lightsource 1. Oppositely, the needle electrode 21 may be arranged in thevicinity of the light source 1 and the cylindrical electrode 22 may bearranged in a position distant from the light source 1 so that heatgenerated by the light source 1 is drawn with the ion wind generator 20.

FIG. 3 shows a structure of the ion wind generator 20A and its layout.The ion wind generator 20A is so constructed that plural needleelectrodes 21A are arranged in parallel or approximately in parallel andplural electrodes 22A corresponding to the needle electrodes are alsoarranged in parallel or approximately in parallel. That is, the ion windgenerator 20A is equivalent to an assembly of plural ion wind generators20 arranged in parallel or approximately in parallel, which means thatsome of electrodes 22A form cylinder portions adjoining each other.Accordingly, in such a configuration that plural ion wind generators areassembled and arranged in parallel or approximately in parallel, thewind power (the amount of wind) is increased. The direction of windgenerated by the ion wind generator 20A is opposite to the light source1, that is, the air supply port of the ion wind generator 20A isdirected to vents 19 of the casing of the projector. When an air currentgenerated by the ion wind generator 20A is exhausted through the vent19, ambient air heated to high temperature by the heat produced by thelight source 1 is drawn and exhausted from the vents 19 on the aircurrent. Since ultraviolet ray is introduced to the position inside thevents, the amount of ozone exhaustion from the projector is reduced.Furthermore, it can be considered that an exhaust cylinder leading tothe vents 19 is provided and the ion wind generator 20A is providedinside the cylinder which is partly made of ultraviolet transmissionglass. This would make it possible to improve the exhaust efficiencywhile decomposing ozone by applying ultraviolet ray.

FIG. 4 shows a configuration in which an ion wind generator 20B isattached to a reflector of a light source 1. A transparent cover 1 a isprovided on the light exit side in order to prevent fragments of glassfrom flowing all over the place in case of burst of a light emitter 2 ofthe light source 1. In order to prevent the temperature of the airinside the light source from increasing, with the transparent cover 1 aclosed, cut-outs 3 a and 3 a are formed on both sides of a reflector 3to release air in high temperature. The ion wind generator 20B comprisesa needle electrode 21B and a cylindrical electrode 22B. The cylindricalelectrode 22B is formed in a roughly semi-cylindrical shapecorresponding to the shape of the cut-outs 3 a. The ion wind generator20B is attached to only one of the two cut-outs 3 a, and the othercut-out 3 a is used as an exhaust port. Ozone produced by coronadischarges in the ion wind generator 20B is exposed to directultraviolet rays from the light source 1 in the reflector 3, and thenthe ozone is decomposed. That is, the first dichroic mirror 4 andultraviolet ray reflection mirror 17 are unnecessary in such aconfiguration. It is desirable that mesh members are attached to thecut-outs 3 a in order to prevent fragments of glass from flowing allover the place in case of burst of a light emitter 2.

FIG. 5 shows a structure of an ion wind generator 20C. The ion windgenerator 20C comprises a needle electrode 21C and a mesh electrode 22C.Compared with a configuration in which plural cylindrical electrodes arearranged, it is easier to realize the reduced cost and the light weightin a configuration that the mesh electrode 22C is used.

FIG. 6 is a perspective view showing an internal structure of aprojection type video display 40 which is provided with an ion windgenerator 20D. The projection type video display 40 comprises a whitelight source 41, an auxiliary fan 42, a power supply 43, a color wheel44, a video generating optical system 45, a projection lens system 46,and a signal processing circuit 47. The ion wind generator 20D is soarranged as to occupy almost entire surface of one side of the casingwhich is closer to the white light source 41. The ion wind generator 20Dis provided with plural needle electrodes 21D as electrodes on one sideand said mesh electrode, for example, as an electrode on the other side.In this way, in a configuration that a lot of needle electrodes 21D arearranged with occupying almost entire surface of one side of the casing,the wind power (the amount of wind) is increased. The direction of thewind generated by the ion wind generator 20D is opposite to the locationwhere the white light source 41 is arranged (the direction outward fromthe projector). When an air current generated by the ion wind generator20D is exhausted outward from the casing, ambient air heated to hightemperature by the white light source 41 is drawn to be exhaustedoutside the casing on the air current. Furthermore, since the ion windgenerator 20D is provided with an ozone removal filter 23D, ozone (o₃)produced by discharges is decomposed and removed when the air isexhausted. The ozone removal filter 23D may be constructed byadditionally attaching a catalyst such as manganese dioxide to asupporting body in a honey-comb shape.

In the above-mentioned configuration, plural electrodes 21D arearranged. Other than the configuration, some electrode plates 21E havingplural pointed portions respectively on one side of the edges may bearranged with keeping certain intervals each other as shown in the FIG.7. Each pointed portion of the electrode plates 21E functions as oneneedle electrode. In such a configuration, the structure is simpler andthe assembling process is easier, compared with the configuration inwhich a lot of needle electrodes are arranged. The electrode plates 21Ecan be made by pressing (press-cut) a metal plate, but the electrodeplates in this embodiment are made by etching process. The etchingprocess has such an advantage that the pointed portions can be formedmore easily in an adequate shape (suitable for reducing discharge soundand improving air supply efficiency, and the like).

Though the ion wind generator is arranged in the vicinity of the lightsource 1 in the configurations mentioned above, the present invention isnot limited to the same. The ion wind generator may be arranged atanother location where air is heated to high temperature (the locationnear a liquid crystal display panel, or the like). Also, thepositive-negative relationship between the electrode on one side and theelectrode on the other side in an ion wind generator may be reversed.Other type of ion wind generators having structures different from thespecific configurations mentioned above can be used, as far as ion windgenerators are so constructed that an air current is generated byionization of air or molecules in the air.

In the afore-mentioned configuration, the video generating opticalsystem using three transmission-type liquid crystal display panels isshown, but the present invention is not limited to the same videogenerating optical system. The present invention can also be adoptedwhen other video generating optical system is used.

As described above, the wind blower according to the present inventionhas a mechanism that produces ion wind. As a result, unlike a windblower that generates a wind by rotating a fan, the wind blower of thepresent invention produces no rotation noise and reduces noises up toalmost soundless state when air is sucked and exhausted. In theconfiguration that the ultraviolet ray emitted from the light source isspectrally separated to irradiate to a wind generated by the wind blowerand in the configuration that the ozone removal filter is provided,there is an advantage in that ozone is prevented from being exhaustedoutside the projector, even if ozone is generated.

1. In a projection type video display that modulates light emitted froma light source with a light valve to project the modulated light; aprojection type video display characterized in that there is provided awind blower which generates an air current by ionizing air and moleculesin the air using an electrode on one side and drawing ions generated bythe ionization by an electrode on the other side, and in that anultraviolet ray emitted from the light source is spectrally separated toapply to a wind generated by the wind blower.
 2. In a projection typevideo display according to claim 1, a projection type video displaycharacterized in that plural electrodes on one side are arranged andplural electrodes on the other side corresponding to said electrodes onone side are arranged in parallel or approximately in parallel.
 3. Inthe projection type video display according to claim 1, a projectiontype video display characterized in that plural electrodes on one sideare arranged and a mesh electrode as an electrode on the other side isarranged.
 4. In the projection type video display according to claim 1,a projection type video display characterized in that an electrode onone side comprises a metal plate having plural pointed portions on anedge.
 5. In the projection type video display according to claim 4, aprojection type video display characterized in that a mesh electrode isarranged as an electrode on the other side.
 6. In the projection typevideo display according to claim 4 or 5, a projection type video displaycharacterized in that the plural electrodes on one side having pluralpointed portions are arranged with keeping certain intervals each other.7. In the projection type video display according to claim 4 or 5, aprojection type video display characterized in that the electrode on oneside having plural pointed portions made by etching metal plate.
 8. In aprojection type video display that modulates light emitted from a lightsource with a light valve to project the modulated light; a projectiontype video display characterized in that there is provided a wind blowerwhich generates an air current by ionizing air and molecules in the airusing an electrode on one side, or upstream side of air current, anddrawing ions generated by the ionization by an electrode on the otherside, or downstream side of air current and, a plurality of saidelectrodes on one side are arranged and as an electrode on the otherside, a mesh electrode is arranged so as to cross the direction of aircurrent.
 9. In a projection type video display that modulates lightemitted from a light source with a light valve to project the modulatedlight; a projection type video display characterized in that there isprovided a wind blower which generates an air current by ionizing airand molecules in the air using an electrode on one side, or upstreamside of air current, and drawing ions generated by the ionization by anelectrode on the other side, or downstream side of air current and, saidelectrode on one side comprises a metal plate having plural pointedportions on an edge.
 10. In a projection type video display according toclaim 9, a projection type video display characterized in that a meshelectrode is arranged as an electrode on the other side.
 11. In theprojection type video display according to claim 9 or 10, a projectiontype video display characterized in that a plurality of said electrodeson one side having plural pointed portions are arranged with keepingcertain intervals each other.
 12. In the projection type video displayaccording to claim 9 or 10, a projection type video displaycharacterized in that the electrode on one side having plural pointedportions made by etching metal plate.
 13. In the projection type videodisplay according to claim 1, 8, or 9, a projection type video displaycharacterized in that the wind blower is located in the vicinity of thelight source having a reflector so as to exhaust heat generated by thelight source outside from the video display and, the wind blower isprovided at the back of the reflector.